Demonstrations are expected to begin around 10am today with members of the so-called Convoy to Canberra group setting off in Commonwealth Park and moving through to Parliament House.

READ MORE: Live updates on Saturday's protests in Canberra

"Canberrans are asked to avoid this area. There will be major traffic disruptions and diversions and Commonwealth Avenue will be closed for a period of time," Australian Federal Police's commander of operations Linda Champion said.

The protesters are made up of a number of loosely affiliated groups, such as sovereign citizens, anti-vaccine conspiracists and evangelicals, but have been demonstrating together against vaccine mandates.

Police expect 4000 protesters will participate today, calling it a "significant" day of protest activity.

However, Lifeline's chief executive officer Carrie Leeson said "10,000 to 15,000" people descended on EPIC overnight, forcing the closure of its bookfair.

Police said earlier that protests so far had largely been "peaceful and within the law".

"We will have numbers where we need to have them so that [Canberrans can continue their day-to-day]. There will be disruptions of course we acknowledge that," Commander Champion said.

"But as for safety, that's why we're out there and we've got full strength on [Saturday] to do so."

Commander Champion also said police were aware of online activity suggesting some protesters would attend Canberra's mass vaccination hub today, as walk-in appointments opened up to five- to 11-year-olds.

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Staff at the Australian Institute of Sport vaccination hub will dress up in superhero costumes in an effort to create a welcoming environment for the kids. The percentage of this cohort which had received a first dose had reached 75.1 per cent on Friday.

"We're very confident that ACT Policing have this tomorrow [Saturday] and we'll work together with them and do our very best to make it a really positive experience for children tomorrow," Canberra Health Service's Katherine Wakefield said.

"Whilst we don't anticipate anything unlawful going on, we do want to make sure we are there with the sufficient numbers to ensure the safety of all the children and parents turning up for the clinic," Commander Champion said.

She did not provide further detail on the police presence, but said: "What we don't want to do is interrupt the safety and security of our children, nor intimidate them with our large numbers, either."

Some protesters have told The Canberra Times they do not intend to comply with eviction notices, though the majority have stated they will look for alternative arrangements.

Commander Champion said police were "really hoping that most move on naturally, that they'll be going home after the big day".

"Those that stay behind, we will be talking to them as we do with any people that we want to move on. If we need to, we will do more actions as required," she said.

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ACT Chief Minister Andrew Barr on Friday said a payment of about $25,000 was made to book the camp sites, but there were more people on the site than there were sites.

The ACT government later clarified the money was paid in a lump sum, but by a number of people

The group began camping at EPIC after they were moved on from an illegal campsite near the National Library last week.

The Lifeline bookfair organisers decided to close on Saturday after influx of campers at EPIC compromised the site's safety.

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